1. Field of the Invention
The present invention relates generally to a housing for an in-vehicle electronic control unit, which is a box-shaped housing for an electronic control unit that is used for an occupant crash protection such as an air bag for protecting an occupant when a vehicle collides, and more particularly to a housing for an in-vehicle electronic control unit that protects a control circuit board disposed in a housing when a vehicle collides.
2. Description of Related Art
Conventionally, as a housing for an in-vehicle electronic control unit such as the above-described type, there is a housing for an electronic device described in JP-A-2008-41718 (corresponding to EP1,887,842A1). As shown in FIG. 10, a housing 100 is a housing of an electronic control unit (ECU) of a vehicle, and includes a base 30 and a case 20 that accommodate a circuit board 10, on which an electronic component 12 is mounted. The housing 100 is attached to an attachment body (not shown) such as a vehicle. The base 30 is formed by pressing aluminum, and includes a holding part 31, an attachment portion 33, and a joining part 36. The circuit board 10 is fixed onto the holding part 31. The attachment portion 33 is screwed to the attachment body and has a through hole 34 through which a screw passes. The joining part 36 connects the holding part 31 and the attachment portion 33. At least one of the attachment portion 33 and the joining part 36 serves as a stress absorption part for absorbing stress produced by the attachment body.
Accordingly, by at least one of the attachment portion 33 and the joining part 36 functioning as the stress absorption part for absorbing stress produced by the attachment body, transmission of the stress produced by the attachment body to the circuit board 10 is limited.
However, in the above-described publication JP-A-2008-41718, if the electronic device housing 100 is damaged after the housing 100 cracks due to deformation of the vehicle when the vehicle collides, for example, the circuit board 10 is also damaged or, the case 20 cracks and rain water or radiator liquid, for example, enters through this crack. As a result, the circuit board 10 is submerged, so that the electronic component 12 mounted on the circuit board 10 is damaged.
For instance, stored data at the time of the collision is retrieved from a storage device of the ECU so as to analyze the collision. Nevertheless, when the circuit board 10 is damaged as above, the analysis of the collision by retrieving the stored data at the time of the collision from the storage device mounted on the circuit board 10 cannot be carried out. Furthermore, if the electronic device housing 100 is damaged, a power source line is short-circuited so as to catch fire, so that a vehicle fire may be caused.